Attachable test device for a flash device

ABSTRACT

A photographic camera provided with a circuit composed of an indicating lamp connected to one of a pair of terminals on the camera which terminals are connectable respectively to synchroterminals of a flash device. A shunting condenser is connected in parallel with the indicating lamp, and a circuit having a resistance and a manually operative test switch in series, in parallel with a synchronizing switch is connected between the other of the pair of terminals and the indicating lamp and condenser. Thereby, all the flash circuits including a flash tube, the flash device, the synchro-terminals of the flash device and the camera and the electrical connection therebetween may be tested by means of the indicating lamp by the closing of the test switch.

United States Patent Kobayashi et al. 14 1 Oct. 31, 1972 1541 ATTACHABLE TEST DEVICE FOR A 2,543,860 3/1951 Lovi et al ..73/5 FLASH DEVICE 2,625,863 1/1953 Kirwin ..324/51 x 3,200,720 8/1965 Drasch .324/295 x [72] 3,140,422 7/1964 McGee ..340/2s2 x both of Kawanishi, Japan Assignee: Minolta Camera Kabushilti Kaisha,

Osaka, Japan Filed: March 13,1970

Appl. No.: 19,326

Foreign Application Priority Data March 17, 1969 Japan .'......44/20289 Us. 01. .324/51, 95/11 L, 324/ R Int. Cl. ..G01r 31/02, GOlr 31/22 Field of Search ..324/5l, 29.5, 133, 20, 51; 315/120, 129; /10, 11 L; 73/5; 340/252 References Cited UNITED STATES PATENTS Polhemus .324/5 1 Podell ..315/ X McGall ..73/5

57] ABSTRACT A photographic camera provided with a circuit composed of an indicating lamp connected to one of a pair of terminals on the camera which terminals are connectable respectively to synchro-terminals of a flash device. A shunting condenser is connected in parallel with the indicating lamp, and a circuit having a resistance and a manually operative test switch in series, in parallel with a synchronizing switch is connected between the other of the pair of terminals and the indicating lamp and condenser. Thereby, all the flash circuits including a flash tube, the flash device, the synchro-terminals of the flash device and the camera and the electrical connection therebetween may be tested by means of the indicating lamp by the closing of the test switch.

3 Claims, 2 Drawing Figures PATENTEDHB I912 3.701.942

FIG. I'

PRIOR ART F I G; 2

. INVEN'iOR 72%;; ky/m yaw/42w f I, BY vv/ 7 I ATTORNEY ATTACHABLE TEST DEVICE FOR A FLASH DEVICE BACKGROUND OF THE INVENTION In the prior art the causes of failure in flash photography are generally taken to be, first, a defect of the flash bulb itself due to disconnection of a filament secondly, consumption of a battery on the power source side of the flash device or a fault of the condenser and thirdly, had contact between the flash bulb and the socket of the flash device. However, besides the above failures, there are also causes due to; for example, disconnection of a synchro-cord for connecting theflash device to the camera, had contact due to an imperfect connection between the synchro-plug at the end of the synchro-cord and the synchro-terminal of the camera which comprise a large percentage of the causes for the failures and especially in flash photography making use of an electronic flash tube the above causes comprise almost all of the failures.

However, in the prior art a test device independent of the camera, has been provided in the flash device, by which a test of the flash circuit only in the flash device has been carried out. Therefore, troubles due to the above first to third causes can be detected, however, it is impossible to make a test of the connection between the flash device and the camera. Further, the entire flash circuit including that within the inside of the camera, such as the above-mentioned disconnection of a synchro-cord. and an imperfect connection between the synchro-plug and the synchro-terminal, and especially in circuits using an electronic flash tube, the tests thereof are scarcely carried out at the present time.

SUMMARY OF THE INVENTION In the present invention the photographic camera is provided with an indicating lamp connected to one of a pair of terminals on the camera and connectable to the synchro-terminals of a flash device. A shunting condenser is connected in parallel with the indicating lamp. A manually operative test switch is connected in series to a resistor in parallel with a synchronizing switch, which in turn is connected in series between the circuit composed of the indicating lamp and the condenser and the other terminal of the camera. Thereby, tests can be made of all the flash circuits of a flash tube, including the flash device, the synchro-terminals of the flash device, the camera, and the connections therebetween;

The primary" object of the present invention is to permit a camera to test the lighting possibility of a flash device using either a flash lamp or an electronic flash tube when any one of them is provided on the camera.

The second object of the present invention is to provide a test device for a flash device contained in a camera, which permits the camera to simultaneously test the flash circuit in the flash device and the flash circuit in the connection portion between the flash device and the camera, and all of the flash circuits in the camera.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an example of a test device provided on the flash device well known in the prior art, wherein A shows the circuit in the camera and B shows the circuit in the flash device.

DESCRIPTION OF THE PREFERRED EMBODIMENT A test device for the flash device in the prior art is contained in the flash device B as shown in FIG. 1 wherein electrodes of the power source charging cir cuit composed of battery 1 and condenser 2are connected by sockets 3,, 3, for connecting flash tube 4, indicating lamp 5 and test switch 6 in series. The electrodes and flash lamp are connected to synchronizing switch 10 in the camera or the shutter through synchrocords 7,, 7, and synchro-plugs 8,, 8,, connectable respectively to synchro-terminals 9,, 9, provided on the camera body in parallel with indicating lamp 5 and test switch 6.

Meanwhile, in the present invention, as shown in FIG. 2, to one terminal 9, of synchro-terminals 9,, 9, the parallel-connected portion composed of indicating lamp 5 and condenser 11, and another parallel portion composed of test switch 6 and set resistance 12-connected in series to each other--and synchro-switch 10 are connected inseries, and connected to the other terminal 9, of the synchro-terminals, and all of them are contained in camera body A, as a test device.

Further, in flash device B, with flash lamp 4, as shown in FIG. 2 one electrode of the power source comprising battery 1 and condenser 2 is connected to one electrode 8, of the synchro-plug formed on the end portion of synchro-cord 7, through flash lamp socket 3,, and the other electrode 8, is connected to the other electrode of the power source. ,Synchro-plugs 8,, 8, are arranged to connect respectively to synchro-terminals 9,, 9, of the camera. Therefore, by fitting flash lamp 4 in flash lamp socket 3,, 3, and connecting synchroplugs 8,, 8, with synchro-terminals 9,, 9, respectively, and then closing test switch 6 on camera body A,, the charge on condenser 2 flows through flash lamp 4, shynchro-cord 7,, synchro-plug 8,, synchro-terminal 9,, indicating lamp 5, test switch 6, set resistance 12, synchro-terminal 9,, synchro-plug 8,, and shynchrocord 7,. In this case, if flash lamp 4 has no disconnection and is fitted properly in sockets 3,, 3,, indicating lamp 5 is lit as long as synchro-cords 7,, 7, have no disconnection and synchro-plugs 8,, 8, are connected properly to synchro-terminals 9,, 9, respectively.

And in this case, while being charged by condenser 11, indicating lamp 5 requires a slight delay to reach its normal brightness, however, that delay is very short and a brief moment after test switch 6 is closed test lamp 5 is at its normal brightness. Set resistance 12 is provided tocontrol the electric current so as not to light flash lamp 4 even though test switch 6 is closed.

In this manner, the lighting of the indicating lamp indicates that everything is all right in the circuits of flash device B,, including synchro-cords 7,, 7,, the connection of synchro-plugs 8,, 8, and synchro-terminals 9,, 9,. Therefore, in taking a flash photograph, when synchronizing switch 10 is closed, the charging current to condenser 2 and the current of battery 1 flow from flash lamp 4 through condenser 11, test lamp 5 and closing synchronizing switch 10, and accordingly flash lamp 4 is lit.

And, in flash device 3,, having an electronic flash tube, power source terminals 21,, 22, are connected to electronic flash tube 25, and to trigger condenser 22 through resistances 27,, 27, in parallel. One end of trigger condenser 22 is connected to one electrode 8 of the synchro-plugs through primary winding of boosting transformer 24 and synchro-cord 7,. The other electrode 8, of the synchro-plllgs is connected to the other end of trigger condenser 22 through synchrocord 7 and the secondary winding of boosting transformer 24 is connected to trigger electrode 26 of flash discharge tube 25.

Therefore, by connecting synchro-plugs 8,, 8 to synchro-terminals 9,, 9, respectively of the camera body A, in FIG. 2 and connecting power source terminal 21 21, to a relatively high voltage power source, and then closing test switch 6, condenser 22 is discharged through the primary winding of boosting transformer 24, condenser 11, switch 6, and set resistance 12. A high voltage is generated in the secondary winding of 'boosting transformer 24 so that flash discharge tube 25 is triggered to emit light. Therefore, an indication is provided that the flash device is fitted properly in the camera, and thereafter by closing synchronizing switch it is possible to take a flash photograph without fail.

We claim:

1. A circuit for testing the condition of a flash circuit in a camera having a pair of synchronizing terminals connectable to a source for igniting a flash device, comprising:

a housing including terminals connected to said synchronizing terminals with said housing attached to said camera;

an indicating lamp;

a condenser shunted across said indicating lamp for by-passing the discharge current of said source;

a resistance and a manually operative test switch connected in series with one another and in series with said condenser, said resistor, test switch and condenser are parallelly connected across said terminals; and

a synchronizing switch connected in series with said indicating lamp and in parallel with said test switch and said resistor, and with said manually operative test switch closed said indicating lamp is operative to indicate the continuity of said flash circuit and with said synchronizing switch closed the current through said flash device is sufficient for ignition.

2. A circuit as in claim 1 wherein said source comprises a charged condenser, said flash device is an at-' tachable flash bulb connected to one pole of said charged condenser and to one of said synchronizing I terminals and the continuity of said flash circuit is tube and the continuity of said flash circuit and said flash tube 18 determined with said manually operative test switch open and said synchronizing switch closed. 

1. A circuit for testing the condition of a flash circuit in a camera having a pair of synchronizing terminals connectable to a source for igniting a flash device, comprising: a housing including terminals connected to said synchronizing terminals with said housing attached to said camera; an indicating lamp; a condenser shunted across said indicating lamp for by-passing the discharge current of said source; a resistance and a manually operative test switch connected in series with one another and in series with said condenser, said resistor, test switch and condenser are parallelly connected across said terminals; and a synchronizing switch connected in series with said indicating lamp and in parallel with said test switch and said resistor, and with said manually operative test switch closed said indicating lamp is operative to indicate the continuity of said flash circuit and with said synchronizing switch closed the current through said flash device is sufficient for ignition.
 2. A circuit as in claim 1 wherein said source comprises a charged condenser, said flash device is an attachable flash bulb connected to one pole of said charged condenser and to one of said synchronizing terminals and the continuity of said flash circuit is determined with said manually operative test switch closed and said synchronizing switch open.
 3. A circuit as in claim 1 wherein said source comprises a booster transformer including a primary winding connected in parallel with a second condenser across said synchronizing terminals, a trigger electrode connected to the secondary winding of said booster transformer, and said flash device is an electronic flash tube and the continuity of said flash circuit and said flash tube is determined with said manually operative test switch open and said synchronizing switch closed. 